Method and apparatus for a molded tube and peristaltic pump

ABSTRACT

A peristaltic pump ( 10 ) and tube ( 18 ) system are provided. The peristaltic pump ( 10 ) operates to squeeze the tube ( 18 ) and push liquid in the tube ( 18 ) in the desired direction. The tube ( 18 ) is molded, and thus allows for predictable and consistent flow rates.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to pumping systems, and moreparticularly to peristaltic pumping systems.

BACKGROUND OF THE INVENTION

Peristaltic pumps are widely used in various applications, includingapplications in the beverage and pharmaceutical fields, among otherfields. Peristaltic pumps generally operate by compressing a flexibletube or channel with one or more heads (or other mechanisms). The heador heads pinch off a portion of the tube or channel (against either aback or an opposing head) and push fluid in the desired direction.

In some applications, a peristaltic pump itself is used over and overagain and the tube is frequently replaced, such as when a beverageconcentrate is depleted in a beverage system or a medicine is depletedin a pharmaceutical application. In other applications, one tube may beused with the same pump for a relatively long time. In still otherapplications, the pump itself may be disposable along with the tube.

Although peristaltic pumps offer certain advantages, they do noteconomically allow for the kind of reproducible and precise flow ratesthat are often required. In many instances, the inaccuracies result fromthe tubes, which are made with an extrusion process. The extrusionprocess results in variations in the inside diameters of the tubes, aswell as variations in the thickness of the tube walls. Because of suchvariations, as tubes are replaced, different flow rates result from thesame pump. Also, variations occur from pump to pump (and thus system tosystem), because of the differences in the tubes, both in disposabletube applications, and in applications where one tube is used for arelatively long time. It is generally not practical to calibrate systemsto overcome the variations.

Thus, for example, where a beverage concentrate is to be pumped at aspecific flow rate for mixture with water at a given ratio, tubevariations result in inaccurate mixture ratios—and hence differentquality drinks—from tube to tube. Such beverage systems are often usedin restaurants and convenience stores (among other locations), and thevariations create unacceptable differences in drink quality from batchto batch in the same location, and from location to location. Similarissues are found in other applications, such as those in thepharmaceutical field.

Another problem with prior art peristaltic pumps is that the pump inletside of the tube is often attached to a tube fitment that operates as arestriction to free flow to the inlet to the pump.

Therefore, a need has arisen for peristaltic pump and tube system thatovercomes the limitations of prior art systems.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, methods andapparatus for a molded tube and peristaltic pump are provided whicheliminate or substantially reduce the problems associated with prior artsystems.

In a particular embodiment, a pump for pumping a material is providedwhich includes a motor, a molded tube, and one or more compression headscoupled to the motor and adapted to compress the molded tube for pushingthe material in a desired flow direction. In one embodiment, the moldedtube comprises a first section having a first inside diameter, and asecond section having a second inside diameter greater than the firstinside diameter. In another embodiment, a fitment is coupled to thesecond section. Also, the discharge end of the tube may have an insidediameter greater or less than other parts of the molded tube. The moldedtube may be an injection molded tube.

In another embodiment of the present invention, a fluid delivery systemis provided which includes a peristaltic pump, a molded tube coupled tothe peristaltic pump through which the fluid flows, a supply of thefluid coupled to the molded tube upstream of the peristaltic pump, and adispenser coupled to the molded tube downstream of the peristaltic pump.In one embodiment, the molded tube comprises a first section having afirst inside diameter, and a second section having a second insidediameter greater than the first inside diameter. In another embodiment,a fitment is coupled to the second section. Also, the discharge end ofthe tube may have an inside diameter greater or less than other parts ofthe molded tube. The molded tube may be an injection molded tube.

Particular applications for the present invention include, withoutlimitation, beverage and pharmaceutical applications.

Also provided is a method of forming a molded tube for a peristalticpump, which includes providing a core and a fitment, providing a cavityadapted to mate with the core and fitment, injecting material into thecavity for forming the molded tube around at least a part of the coreand fitment, and ejecting the molded tube and fitment from the core.

In a particular embodiment, the injected material is a thermosettingelastomer. In one embodiment, the molded tube and fitment are ejected bysupplying a gas through the core. In another embodiment, the fitment isformed and then placed on the core. In an alternative embodiment, thefitment is molded in place on the core. In another embodiment, aweakened area may be formed on the molded tube for removing an end ofthe tube, and, if desired, a removal tab may be formed proximate to theweakened area.

In another embodiment, the fitment has a fitment inside diameter, andthe fitment inside diameter is greater than or equal to an insidediameter of a portion of the molded tube not formed around the fitment.In still another embodiment, the molded tube has a discharge end with aninside diameter different than a portion of the molded tube not formedaround the fitment.

One important technical advantage of the present invention is that itincludes a molded tube which allows more precise and repeatable flowrates from peristaltic pumping systems than prior art systems. Anotherimportant technical advantage of one embodiment of the present inventionis that it includes a molded tube which may be formed in combinationwith a fitment. Still another important technical advantage of thepresent invention is that it includes a molded tube which may be formedwith an increased diameter portion which makes it easier to improve flowrates into peristaltic pumping systems.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made in the description to the following briefly describeddrawings, wherein like reference numerals refer to correspondingelements:

FIG. 1 is a block diagram of one embodiment of a peristaltic pump andtube according to the teachings of the present invention;

FIG. 2 illustrates one embodiment of a tube for a peristaltic pumpaccording to the teachings of the present invention;

FIG. 3 is an isometric view of one embodiment of a mold for making atube according to the teachings of the present invention;

FIG. 4 illustrates another embodiment of a tube for a peristaltic pumpaccording to the teachings of the present invention;

FIG. 5 is a cross sectional view of one embodiment of a molding systemfor making a combined fitment and molded tube according to the teachingsof the present invention; and

FIG. 6 is a cross sectional view of the molding system of FIG. 5 in theopen position.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, a peristaltic pump 10 is shown in block form, whichincludes a motor 12, a shaft 14, and head (or heads) 16. Head or heads16 engage a molded tube 18.

The head or heads 16 squeeze the tube 18 (against a back or opposinghead or heads) and push fluid in the desired direction. In theparticular example illustrated in FIG. 1, the fluid comes from a supply20, which may be a bag of fluid, such as a plastic bag used in abag-in-box beverage system, or a pharmaceutical bag, used forpharmaceuticals or other fluids. The supply 20 generally includes asupply fitment 22 that is coupled to a tube fitment 24 through any ofseveral known approaches. The tube fitment 24 may be coupled to the tube18 through any of several known approaches, or as described below aspart of the molding process. Downstream of the pump 10, the tube 18 iscoupled to dispenser 26. Dispenser 26 may be, for example and withoutlimitation, a beverage dispenser or a needle for an injection into apatient, or any other dispensing device, and may also be simply the openend of the tube 18. It should also be understood that the tube 18 ortube fitment 24 may be coupled directly to the supply 20 (or to thesupply fitment 22) and to the dispenser 26, or through any number ofintermediate coupling devices. Of course, the pump may be integratedwith the dispenser or the supply.

Although a peristaltic pump with a motor, shaft, and head isillustrated, any peristaltic pump mechanism may be used, including,without limitation, those that squeeze a tube and move fluid in the tubewith one or more roller heads, sliding heads, caterpillar mechanisms,wave mechanisms, cams, disks, or other devices. Examples of particularperistaltic pumps are described in U.S. Pat. Nos. 5,413,252 and5,558,507, which are herein incorporated by reference in their entirety.The incorporation of these examples is illustrative only, and not by wayof limitation, and thus is not meant to limit the scope of the inventionor to exclude from coverage any other type of peristaltic pumpmechanism. For ease in describing any of the various peristaltic pumpmechanisms, the squeezing mechanism may be referred to herein as acompression head. Also, although the supply 20 is illustrated as aflexible bag, any source may be used.

The tube 18 of the present invention is molded, and is not extruded asare prior art tubes. In a particular embodiment, the molding process isan injection molding process. Because the molding process allows forvery precise tolerances, the kinds of variations found in prior arttubes are substantially or completely eliminated with the molded tube ofthe present invention. It should be understood that any other suitablemolding process may also be used, including, without limitation,compression molding.

FIG. 2 illustrates a particular tube 18, in combination with a tubefitment 24, before being used in a dispensing system such as that shownin FIG. 1. In the particular embodiment shown in FIG. 2, the tube 18includes an end 30 and an expanded diameter section 32. The end 30 is asealed (or otherwise closed) end of the tube 18, and ensures that thetube 18 remains clean before use (at which time the end 30 is removed).It should be understood that the end does not have to be sealed.

The expanded diameter section 32, although not necessary in allembodiments of the present invention, provides a significant advantageover prior art tubes. In particular, by forming the expanded diametersection 32 with an inside diameter greater than that of the main portionof tube 18, the tube fitment 24 (or supply fitment if the tube iscoupled directly to the supply) may have an inside diameter equal to orgreater than that of the main portion of tube 18, and can be easilycoupled to the tube 18 (the tube may also be formed on the fitment, asdescribed below). With such a fitment, flow to the pump inlet side ofthe tube is not restricted (as the diameter is not diminished), and thusthe peristaltic pump is not “starved” and its performance limitedthereby. In some prior art systems, tube fitments cause inlet pump flowrestrictions, as it is difficult to stretch an extruded tube over a widetube fitment. The flow restriction issue is particularly important inpumping relatively high viscosity liquids, such as, without limitation,orange juice concentrate, wherein inlet flow restrictions cansignificantly affect desired flow rates.

The expanded diameter section 32 may be formed in other processes aswell, such as, without limitation, with an expansion mandrel insertedinto the tube 18. Furthermore, the expanded diameter section may beformed with features, such as, without limitation, shoulders, grooves,or lips, to accommodate the tube fitment 24 (or supply fitment) andenhance the fit between them. However, it should be understood that anyapproach may be used to couple the tube with a fitment.

FIG. 3 is an exploded view of one embodiment of a molding system forforming a molded tube 18 according to the teachings of the presentinvention. As shown in FIG. 3, a male plug (or core) 40 is formed on abase 42. A cavity block 44 having a cavity 46 mates with the core 40.Injection material, such as, without limitation, an injection-moldablegrade of a thermosetting elastomer, for example “liquid silicone”rubber, is injected into the cavity 46 and cured around the core 40 toform the molded tube 18 shown in FIG. 3. It should be understood thatother injection materials, such as, without limitation, a thermoplasticelastomer, may also be used.

The particular core shown in FIG. 3 includes a base 48 for formingexpanded diameter section 32. It should be understood, however, that,although desirable, no such base or expanded diameter section isrequired as part of the present invention. As discussed above, it isalso desirable that the top of the tube 18 be closed, and thus the tube18 is shown with a sealed end 30 (which may or may not have the samediameter as that of the main section of the tube). However, it should beunderstood that no such sealing is required as part of the presentinvention. Also, it should be understood that the end of the molded tube18 opposite the section 32 (the discharge end) may be molded to form anyshape desirable for coupling with downstream devices, and thus may havean expanded or reduced diameter. In some applications, for example,without limitation, those with high flow rates or relatively largediameter tubes, dripping is reduced by forming the discharge end with aninside diameter less than that of the main portion of tube 18.

As shown in FIG. 4, the tube 18 may be (but need not be) formed with aweakened area 50 to facilitate easy removal of the end 30. Also, aremoval tab 52 may be formed proximate to the weakened area 50 to allowa user to tear away the end 30 before use of the tube.

The tube 18 may be ejected from the mold system by any suitableapproach. One approach, without limitation, is to inject a gas through agas port 54, which allows gas (such as, without limitation, air) to flowthrough the end of the core 40 to eject the molded tube 18.

FIGS. 5 and 6 are cross sectional views of another embodiment of asystem for molding a tube 18 according to the teachings of presentinvention. In the particular embodiment shown in FIGS. 5 and 6, the tube18 is molded around a fitment 24. FIG. 5 shows the molding system in theclosed position, and FIG. 6 illustrates it in the open position, withthe tube 18 ready to be ejected. The fitment 24 may be of any suitablematerial, including, without limitation, plastic or metal. The fitment24 may be formed in another process and inserted into the mold before itis closed, or molded in place in a shuttle mold system that allows forthe injection of the fitment material and for injection of the tubematerial. If desired, although not required, the materials may be chosenso that they chemically bond to one another. With the embodiment ofFIGS. 5 and 6, a combined tube and fitment are produced, and noadditional step of coupling a tube fitment with the tube is necessary.

An air injection pin 56 is fully inserted during the injection process,to prevent the injection material 58 from entering an ejection channel60. Ejection channel 60 runs from the end of the core 40 to the gas port54. When the air injection pin 56 is retracted, as shown in FIG. 6, thechannel 60 is opened and gas may be blown into the port 54 and throughthe core 40, to eject the tube 18 from the mold. The mechanism shownform ejecting the tube may also be used with the embodiment shown inFIG. 3.

The particular embodiments and descriptions provided herein areillustrative examples only, and features and advantages of each examplemay be interchanged with, or added to the features and advantages in theother embodiments and examples herein. Moreover, as examples, they arenot meant to limit the scope of the present invention to any particulardescribed detail, and the scope of the invention is meant to be broaderthan any example. For example, and without limitation, although beverageand pharmaceutical applications have been illustrated, the presentinvention may be used with any other fluid delivery system. And, ingeneral, although the present invention has been described in detail, itshould be understood that various changes, alterations, substitutions,additions and modifications can be made without departing from theintended scope of the invention, as defined in the following claims.

1. A pump for pumping a material, comprising: a motor; a molded tube;and one or more compression heads coupled to the motor and adapted tocompress the molded tube for pushing the material in a desired flowdirection.
 2. The pump of claim 1, wherein the molded tube comprises afirst section having a first inside diameter, and a second sectionhaving a second inside diameter greater than the first inside diameter.3. The pump of claim 2, and further comprising a fitment coupled to thesecond section.
 4. The pump of claim 2, wherein the first section is adischarge end of the molded tube.
 5. The pump of claim 1, wherein themolded tube comprises an injection molded tube.
 6. A fluid deliverysystem, comprising: a peristaltic pump; a molded tube coupled to theperistaltic pump through which the fluid flows; a supply of the fluidcoupled to the molded tube upstream of the peristaltic pump; and adispenser coupled to the molded tube downstream of the peristaltic pump.7. The system of claim 6, wherein the molded tube comprises a firstsection having a first inside diameter, and a second section having asecond inside diameter greater than the first inside diameter.
 8. Thesystem of claim 7, and further comprising a fitment coupled to thesecond section.
 9. The system of claim 7, wherein the first section is adischarge end of the molded tube.
 10. The system of claim 6, wherein themolded tube comprises an injection molded tube.
 11. The system of claim6, wherein the fluid is a beverage concentrate.
 12. The system of claim6, wherein the fluid is a pharmaceutical.
 13. A method of forming amolded tube for a peristaltic pump, comprising: providing a core and afitment; providing a cavity adapted to mate with the core and fitment;injecting material into the cavity for forming the molded tube around atleast a part of the core and fitment; and ejecting the molded tube andfitment from the core.
 14. The method of claim 13, wherein the injectedmaterial comprises a thermosetting elastomer.
 15. The method of claim13, wherein ejecting comprises ejecting the molded tube and fitment bysupplying a gas through the core.
 16. The method of claim 13, whereinproviding a fitment comprises forming the fitment and placing thefitment on the core.
 17. The method of claim 13, wherein providing afitment comprises molding the fitment in place on the core.
 18. Themethod of claim 13, and further comprising forming a weakened area onthe molded tube for removing an end of the tube.
 19. The method of claim18, and further comprising forming a removal tab proximate to theweakened area.
 20. The method of claim 13, wherein the fitment has afitment inside diameter, and the fitment inside diameter is greater thanor equal to an inside diameter of a portion of the molded tube notformed around the fitment.
 21. The method of claim 13, wherein themolded tube has a discharge end with an inside diameter different than aportion of the molded tube not formed around the fitment.